(458a) Sorption of Organic Acids on Weak-Base Anion Exchange Resins with Different Basicities

There has been a rapid shift in recent years in the utilization of resource base from fossil fuel feedstocks to renewable feedstocks for the production of value added chemicals. By the year 2025, bio-based production of these chemicals is expected to contribute to at least 25% of the total production. Production methods based on fossil fuels are cost-effective and efficient due to highly optimized processes in the chemical manufacturing sector. Emerging technologies in metabolic engineering and bio refineries are helping biobased industries to compete more effectively with the chemical industries to bring products to the market. Among value added chemicals, organic acids belonging to the carboxylic acid group are considered important platform chemicals. In particular, acetic acid and lactic acid have large market potentials due to their numerous applications in the food and chemical industries. However, to achieve market viability, the downstream processing costs of separation and purification of the acids from the fermentation broth, a major cost component of the total product cost, should be significantly reduced.

Ion exchange using weak-base anion exchange resins has proven to be an economic and efficient method for the separation of organic acids. In this research, the uptakes of acetic and lactic acids on several resins of different basicities were studied. Experiments were conducted at different pH values to determine the effects of the pH of the solution, pKa of the acid, and the pKa of the resin on acid sorption from pure solutions, mixtures of lactic and acetic acids, and from fermentation broths. The resins studied include Reillex 425 and a more basic resin Purolite A835. Sorption data for pH range from 2 to 10 for lactic and acetic acids along with equilibrium models and mechanistic analysis of resin basicity will be presented.